While not stamped Coro Duette, the frame is stamped with BRIT. PAT. 410696 and CAN. Pat. 347175 and both of the individual dress clips are stamped PAT. 1852188. The Patent Number 1852188 was issued to Elias Phinney in 1932 for Cohn & Rosenberger, who Coro was named for. This is early 30s, and the safety catch on the brooch frame must be in the open position to remove the clips.
Brooch is 1" long x 2.5" wide, silver tone
Safety clasp in good working order
All stones present and bright